Although in recent decades our understanding of the molecular mechanisms of taste reception has advanced, how the taste information is transmitted and coded in the nervous system remains unclear. Our long-term objective is to understand the coding system of gustatory information, from taste receptor cells to the central nervous system. In this proposal, we aim to develop genetic tools that will greatly contribute to our understanding by concurrently elucidating precise gustatory neural pathways within the same animal, and then use these tools to test our hypothesis that gustatory information for different taste modalities is transmitted via specific ascending neural pathways. One well-known genetic tracer is wheat germ agglutinin (WGA), which was developed ten years ago. In the research we propose here, we will engineer various WGAs that integrate specific tags such as Myc peptide, FLAG peptide, and enhanced green fluorescent protein, and will evaluate their tertiary structure by molecular dynamic simulation. We will evaluate the resultant engineered WGAs in terms of their intracellular stability and lectin activity in vitro. We will then induce their expression in mice in a subset of taste receptor cells under the control of promoters/enhancers of taste reception-related genes and evaluate their utility in vivo. From these studies, we expect to develop a minimum of two tagged WGA- based genetic tracers that are available to label multiple gustatory pathways concurrently and distinguishably. These tracers should be of great use not only in our future gustatory research but in studies of olfactory and somatosensory systems and many other areas of neuroscience research that study the genetics of interconnected pathways. PUBLIC HEALTH RELEVANCE: This proposed research aims to develop new genetic tools to label multiple neural circuitries concurrently and distinguishably. These tools will contribute to elucidating relationships between multiple neural pathways for different taste modalities. They will also contribute to other neuroscience research, including studies of olfactory and somatosensory systems.